Eur. J. Nucl. Med. 2, 217-218 (1977) European MI IPll::~Qr Journal of I ll~i~Jl~.,,~l Medicine © by Springer-Verlag 1977 Value of Radioisotope Axial Tomography in the Diagnosis of a Cystic Malignant Glioma J.M. Carril 1, R.J. Fraser 2, and J.R. Mallard t t Department of Medical Physics, University of Aberdeen, Aberdeen, Scotland 2 Department of Neurosurgery, Aberdeen Royal Infirmary, Aberdeen, Scotland Abstract. A case is presented in which the patient had a deep tumour in the posterior aspect of the temporal lobe close to midline. The brain scan includ- ing a transverse section view at 8 cm from the vertex was negative and the other neuroradiological exami- nations inconclusive. One month later a follow up brain scan was performed and the conventional views were negative whereas the transverse section scan done at 10 cm from the vertex showed a lesion in the left temporo-parietal region and near midline. Three months later a repeat brain scan was done, and the lesion was visualized in the conventional views and confirmed by angiogram. Introduction Radioisotope Axial Tomography, the principles of which were introduced by Kuhl (1964), is a new tech- nique which provides us with a transverse section image at the level selected, so that by separation, improved localization and improved counting statis- tics, difficulties inherent in the position of the lesion and its low uptake may be overcome. In this sense, this technique clarifies the real significance of doubt- ful uptakes found in conventional views and may show, as in the case we report here, pathological up- takes which were undetected in conventional scan- ning. Case Report A 36 year old man was admitted as an emergency after an episode of unconsciousness preceded by an apparent smell of burning and disturbance of vision characterized by images flashing across his For offprints contact." Prof. Dr. J.R. Mallard right field of vision. On admission he was fnlly conscious, with only slight memory impairment. Physical examination revealed no abnormality. On the evening of admission the patient suffered a classical grand mai seizure. Fundi were normal and lumbar puncture revealed no CSF abnormality. Brain scan, including transverse section scan at 8 cm from the vertex, was done on the ASS (Aberdeen Section Scanner) (Bowley et al., 1973) and all the views were normal. Neuradiolog- ical examinations by angiography and pneumoencephalography gave contradictory information. The patient was discharged, to be followed up and treated with Phenobarbitone and Phenytoin, and a repeat brain scan arranged for 4 weeks later. On the second admission the patient revealed that he had suffered minor fits, with visual and auditory aura and developed a diplopia. A second brain scan was done and since a temporal lesion was suspected from the clinical symptoms, a deeper level was selected for the transverse section view (10 cm from the vertex). The four conventional views were normal (Fig. 1), but the to- mographic view showed a pathological uptake in the left temporo- parietal region (Fig. 2). The patient was discharged again and treated with Phenobarbitone and Phenytoin. Three months later he was readmitted with more frequent attacks and frontal headache. He had lost weight (3 stones) and his memory and concentration were poor. Neurological examina- tions showed: right homonymous hemianopia, right facial weak- ness, and tremor of the tongue. This time the brain scan showed the lesion in the left lateral view. A left carotid angiogram now revealed a large occupying lesion with small pathological circula- tion, in the left temporal lobe. At operation (Mr. R.J. Fraser), a cystic tumour containing I5 ml of fluid was found in the posterior aspect of left temporal lobe. A subtotal excision was carried out. Pathological examination revealed it to be a malignant glioma with astrocymatous and oligodendrogliomatous components. Discussion Radioisotpe brain scanning is a well established procedure for the diagnosis of intracranial lesions, and the overall accuracy, as found in authoritative reviews is about 80 90% (Quinn et al., 1965 ; Mallard, 1971; Burrows, 1972). But this figure, although ac- ceptably good implies that about 10-20% of incor- rect results remain.